Internationalize recently introduced content

_locales/bg/messages.json

_locales/da/messages.json

_locales/de/messages.json

_locales/el/messages.json

_locales/en_GB/messages.json

_locales/en_US/messages.json

_locales/es/messages.json

_locales/fi/messages.json

_locales/fr/messages.json

_locales/id/messages.json

_locales/is/messages.json

_locales/it/messages.json

_locales/ja/messages.json

_locales/nl/messages.json

_locales/pl/messages.json

_locales/pt_PT/messages.json

_locales/ru/messages.json

_locales/sv/messages.json

_locales/zh_CN/messages.json

_locales/zh_TW/messages.json